Variation in genotypic response to copper deficiency in Pinus radiata.  L. A. Pederick, P. Hopmans, D. W. Flinn and I. D. Abbott.  October 1983.  13 pp. (unpubl.)

SUMMARY

Severe malformation of Pinus radiata D. Don (radiata pine) in a fast-growing, six-year-old progeny trial growing on a former farmland site at Toorour, in the Warrenbayne Plantation, North-eastern Victoria, was found to be due to copper deficiency.

The symptoms were: angular kinking (of varying degree) of the stem and/or branches and in some trees pronounced bending and curvature of the stem, even looping of the stem in extreme cases; thickened branches; sometimes death of the leading shoot followed by development of multiple leaders. These symptoms agree with those described in published accounts of copper deficiency for P. radiata and other conifers.

The progeny trial at Toorour contained 49 families of trees in row plots of 10 trees, with most families replicated eight times. The malformations of the trees were rated qualitatively according to a 1-6 scale of increasing severity.

Significant differences in mean malformation score were found among the families (range 1.78-4.82), with some families characterised by trees with little or no malformation, and other families having many members with gross malformation. When those families with a common parent were formed into groups there were significant differences between the group means (range 1.97-4.37), thus indicating that the response to copper deficiency was inherited. The mean malformation score of each family bore no relation to its mean foliar concentration of copper, which indicates that the families varied in efficiency of copper usage.

The average concentration of copper on one-year-old foliage per family ranged from 4.9 to 6.6 ppm, which is higher than the values of 1-3 ppm reported in the literature for copper deficiency. However, the copper concentration in the soil beneath the pines was only 1.1 ppm, a low figure by agricultural standards. High levels of phosphorus were present in the soil, attributable to residual phosphorus from fertiliser applications during agricultural cropping, and foliar levels of the nutrients: nitrogen, phosphorus and potassium, were all high. The fast growth rate of the trees was thus attributed to an abundance of primary nutrients and favourable growing conditions.

The copper deficiency seems to be an induced one. Although the availability of copper appears adequate under normal conditions (no malformation was observed on sites that had formerly carried native forests), the ex-farmland sites (with residual fertiliser) could not meet the higher need for copper to sustain the more rapid growth rate. Copper deficiency symptoms have recently been observed at other former farmland sites in this and other plantation areas in North-eastern Victoria.

Results suggest that breeding is not a practical solution to the problem of copper deficiency. The use of cuttings of clones selected for low-copper tolerance could be considered, and the treatment of low-copper sites with a copper fertiliser is being investigated.

Also published:

Pederick, L.A., Hopmans, P., Flinn, D.W. and Abbott, 1.D. (1984)  Variation in genotypic response to suspected copper deficiency in Pinus radiata.  Aust. For. Res. 14 (2): 75-84.